Steam-boiler.



Uren TATES ATnNT OFFICE.

ANDREAS GRNVALD, OF BROCKTON, MASSACHUSETTS, ASSIGNOR OF ELEVEN-TVELFTHS TO OSCAR F. PETERSON, CHARLES R. ANDERSON, AXEL E. PETERSON, AND CHARLES F. DAIAILBORG, OF SAME PLACE.

STEAM-BOILER'.

SPECIFICATION forming part of Letters Patent No. 668,816, dated February 26, 1901.

Application tiled November l, 1900. Serial No. 35.172. (N0 mdel.)

To all whom it may concern,.-

Beit known that I, ANDREAS GRNVALD, a citizen ofthe United States, residing at Brockton, in the county of Plymouthrand State of Massachusetts, have invented certain new and useful Improvements in Steam-Boilers; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has relation to improvements in steanrboilers, and particularly to steam-boilers of the fire-tube type.

The object of the invention is to provide a boiler of this character having a novel construction and arrangement of parts whereby a larger proportion than usual of the heat units from the hot air, smoke, and products of combustion rising from the bed of fuel is utilized and a material saving in fuel effected.

According` to this invention the hot air, smoke, and products of combustion rising from the bed of fuel on the grate circulate in the usual manner from the lire-box beneath the boiler to the back of the boiler and thence return to the front through the fire-tubes, passing from said tubes into the ordinary smoke box or drum at the front of the boiler; but instead of discharging at this point into the smoke-stack the smoke and gases pass downward through an intervening liue provided for that purpose and thence discharge into the smoke-stack. By this construction the outflow of the smoke and gases is checked or retarded, owing to the disinclination of the same to taking a downward course, and a pressure in the said smoke box or drum is created, resulting in the utilization of a large proportion of the heat ordinarily wasted and a consequent saving in fuel. The flue is provided with a damper or regulator by which the downward and outward circulation of the smoke and gases may loe controlled.

In the accompanying drawings, Figure l is a vertical longitudinal section ofa steamboiler constructed in accordance with my invention. Fig. 2 is a vertical transverse section of the same on line 2 2 of Fig. 1.

Referring now more particularly to the drawings, the numeral l represents a fire-tube munication at one side with a downdraft-iue `8, which is provided at a suitable point with a damper or regulator 9 and connects at its lower end with a horizontal draft-tine 10, leading from the ash-pit 4 to the smoke-stack 1l.

12 and 13 are clean-outs located, respectively, at the base of the downdraft-ue and at the base of the smoke-stack.

The operation is as follows: The hot air, gases, smoke, and other products of combustion rising from the bed of fuel on the grate pass along the bottom of the boiler to the rear of the boiler and then back to the front through the fire-tubes 2. On entering the boX or drum 7 the smoke and gases instead of discharging, as usual,directly to the atmosphere are checked or retarded, owing to the disinclination of the same to take a downward course. The smoke then being heavier than the hot air descends first and under the pressure or tension of the following hot air which is therebycreated is forced downward through the iue 8 and into the flue 10 and discharges to the atmosphere through the smoke-stack 11. By thus checking or retarding the circulation of the smoke and gases a large proportion of the heat ordinarily allowed to go to Waste is utilized and a material saving in fuel effected, and at the Same time a rapid discharge of the smoke and other heavier particles of the products of combustion is insured. The purpose of the fine l0 is to promote the draft at the base of the downiiue 8 and through the ash-pit 4. A rapid discharge of the smoke and gases on entering said flue is thereby provided for. On starting up the boiler a fire may first be made in the ash-pit to force the dead air out of the iire tubes and iiues preliminary to starting the regular lire on the grate. To prevent the e11- IOO what I claim, and desire to secure by Letters Patent, is-

In a boiler, the combination with the firebox and ash-pit, and the boiler provided with the fire-tubes and drum, of a smoke-stack, a downdraft-fiueleading from the outlet of the drum, a horizontal draft-flue leading from the smoke-stack to the ash-pit and communieating with said do'wndraft-iiue, a damperin the downdraft-flue, and a door or damper for opening and closing the inlet of said draft- Iiue to theash-pit, substantially as described.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

ANDREAS GRNVALD.

Witnesses:

GEORGE E. FISHER, JOHN JACKSON. 

